Process of treating sulphide ores of lead, silver, and copper



Patented Mar 4, 51924.

- omen stares PATENT I OFFICE. I

NIELS C. CHRISTENSEN, OF SALT LAKE CITY, UTAH.

rnocnssor TREATING SULPHIDE ones or Lani), SILVER, AND corrnn.

No Drawing. Original application filed October 8, 1919, Serial No.329,397. Divided and this application" To all whom it may concern:

Be' itknou'n that I, Nmns C. Cirm'srnN- sen; a"citiZen of the UnitedStates, residing at Salt Lake City, in the county of Salt.Lali'ehndstate of Utah, have invented cerany preliminary oxidizing,sulphatmg or chloridizmg roast.

My (process consists in treating the finely groan ore with a hotconcentrated "solution "of one or more of the common chlorides-containinala small amount of ferric chlo- A ride. Eit

er ferric chloride-or ferric sulphate may be used, but the former ispreferabl'e in order to avoid contamination of the solution withsulphates. 'The ferric sulphate added .to the concentrated chloridesolution forms ferric chloride immediately, but the sulphates build upin the solution and decrease the solubility of the metal chlorides.

I have found that a hot solution of any of the common chlorides such asNaCl, CaCl MgCl or FeCl containing a small amount of ferric chloriderapidly dissolves galena, afiglelntite and chalcocite. Solutions of KCl,G1 and MnCl containing ferric chloride also act in the same way butwould rarely be used. Zinc chloride solution actsvsimilarly but is muchless active owing to the more limited solubility of the silver; lead andcoppe chlorides in this solution. Ferric chloride alone is theleastsuitable oi the'chlorides for use as the concentrated; solution of:the process as well as to thevery slight solubilitv of the chlorides oflead'and silver inst-concentrated ferricchloride solution, and aconcentrated ferric chloride solution is entirely unsuited to theprecipitation of the free metals therefromas the entire solution wouldhave to be reduced to the ferrousv condition before the orides) could beH h 'tsn ti s would be 'used'i'n most cases in my pres ncantatmm:

filed October 4; 1922.

Serial No. 592,408.

process are those containing NaCl, or a mixture of NaCl and some of thefollowing: C-aCl MgCl and FeCl In some places where cheap CaCl isobtainable it might be used in preference to NaC-l. The action of theferric chloride, contained In the concentrated chloride solution,-on thegalena, argentite, and chalcocite is indicated The lead, silver andcopper are dissolved as i very rapid and i somewhat sloweron'thechalcocite and still. slower on the argentite. The silver contained inthe galena is'brought into solution just as rapidly as the galena. "lhetime of treatment necessary to bring the metals into solution will varywith the fineness of grinding, the temperature of the solution, theconcentration of the ferric chloride in the solution, and theconcentration of the lead, copper and silverchlorides in the solution.Fine grinding approaching 100 mesh or finer is preferable in most cases.The solutions not most vigorously near the boiling point of the solutionandhot solutions are preferable in all cases. A slight excess of ferricchloride above the amount theoretically necesmry to bring the metalsinto solution is desirable but a large excess is not, necessary and isnot advantageous in the practical operation of the process. As theconcentration of thesolution in lead, silver and copper increases therapidity of the action decreases and becomes extremely slow as thesolution nears saturation, so that it is not advantageous to attempt touse solutions too near saturation vin regard: to the lead, silver andcopper. A treatment of from 15 to 30 minutes with a hot solutioncontaining a small percoi'itage of, excess ferric chloride is suflicicntto bring the lead, silver and copper into solution. The S. given offduring treatment may be collected without difficulty as it rises to they ground ore or concentrate with the hot chloride solution until thelead, silver and copper are in solution, and then decanting or filteringthe hot pregnant solution away from the ore. It is advantageous to havea small amount of HCl present in the solution to reduce. the hydrolysisof the ferric chloride and prevent precipitation offer'ric hydroxide.

The method of precipitation of the metals from the pregnant solutionwill vary with the quantity and number of metals in the ore and theproducts desired. If the ore contains only galena, the solution may becooled and the lead chloride separated as described in my patentapplication Serial Nos. 327,400 and 327,401, or the lead may beprecipitated by electrolysis as described in application No. 327,401. Ifthe solution contains silver this is preferably precipitated withmetallic lead before the precipitation of the lead or lead chloride. Ifthe solution contains copper as well as silver and lead the silver ispreferably first precipitated with metallic copper, the copper thenprecipitated with metallic lead, and the lead'finally preci itated byone of the methods mentioned. The silver or copper may also beprecipitated with metallic iron, as may also the lead, but the iron actsslowly upon the lead chloride in the concentrated chloride solutions,and the other methods for the precipitation of the lead are preferable.vAs before mentioned the exact method of preci itation will depend uponthe contents of t e ore and the products desired. My preferred method ofprecipitation of the lead from solution is to electrolyze in a cell witha diaphragm between the anode and cathode compartments, the solutionfirst passing into the cathode compartment where the lead isprecipitated, and then into the anode compartment where the ferrouschloride is changed to ferric chloride, thus regenerating the solutionfor the treatment of more ore.

If the lead is precipitated as a chloride by a coolin my preferredmethod of treatment is to e ectrolyze the melted lead chloride to securelead and chlorine, and to pass the chlorine thus generated into theferrous chloride solution and thus regenerate the ferric chloride forthe treatment of more The chloride solution does not act upon py'site orchalco-pyrite, or upon some of the complex arsenical silver minerals,but does act upon zine blende to a limited extent. It is practicallyimpossible however, to secure a complete extraction of the zinc unless avery large volume of solution containing a considerable excess of ferricchloride is used. The process is therefore not well ada ted to thetreatment of zinc sulphide ores for the recovery of the zinc but issuitable for the recovery of the lead from these ores, as the solutionacts more rapidly on the galena than the blende.

As before mentioned any of the common chlorides except zinc chloride andferric chloride may be used as the main solution in the process, butthose ordinarily used will be NaCl or CaCl or a mixture of NaCl withother chlorides.

As it is obviously impossible to describe all the variations in'thedetails of the appli cation of my process to all kinds of ores, I do notwish to be limited by an foregoin brief description but by the appendeclaims.

By my process I have secured practically complete extractions of thelead and silver from galena ores and concentrates, and have securedpractically complete extractions of the lead and silver and copper fromthe ga lena and chalcocite in ores containing these minerals togetherwith pyrite and chalcopyrite, and have left the pyrite and chalcopyritein excellent condition for recovery by flotation. The silver and copperlocked up in the pyrite and chalcopyrite are recovered with theseminerals. By my process I have also made practically completeextractions of the copper in the form of chalcocite in copperconcentrates and extractions of from 95--98% of the silver inorescontaining the silver as a sulphide.

From the foregoing it will be apparent that my process as 9. eat manadvantages over the old metho s in whic the ore is subjected to anoxidizing, sulphating or.

chloridizing roast and thereafter lixiviated for the recovery of themetals, both in the cost, simplicity of treatment and completeness ofextraction.

This application is a division of my aplication erial No. 329,397, filedOctober 1919, the application having been divided ursuant to t erequirements of the United tates Patent Ofiice.

- By the term chloride brine used in this s ecification, and in theclaims, is meant a c loride solution consisting mainly of such chlorideas sodium chloride, calcium chloride, magnesium chloride, etc., whichform the common brines, as distinguished from the metallic chloridessuch as those of zinc, copper, mercury, etc., though in the treatment ofores minor quantities of the chlorides of zinc, iron, manganese, etc.,will be introduced into the, solution.

Wha is claimed is,-

1. T e process of treating ores containing some of the sulphide mineralsof lead,

silver and copper, which consists in treating said ores with a hotconcentrated chloride brine solution containing ferricchloride andthereby dissolving the metals of said minerals in said solution aschlorides.

2. The process of treating ores containing some of the sulphide mineralsof lead, silver and copper, which consists in treating said ores with ahot concentrated chloride brine solution containing ferric iron insolution and thereby dissolving the metals of said minerals in saidsolution as chlorides.

3. The process of treating ores containing some of the sulphiden'iinerals of lead, silver and copper, which consists in treating saidores with a hot concentrated chloride brine solution containing ferricchloride and thereby dissolving the metals of said minerals in saidsolution as chlorides. and separating said pregnant solution containingsaid metal chlorides, and precipitating the silver with metallic copper,the copper with metallic lead and the lead a chloride by cooling saidhot solution.

4. The process of treating ores containing some of the sulphide mineralsof lead, silver and copper which consists in treating said ores with ahot concentrated chloride brine solution containing ferric chloride, andthereby dissolving the metals from said minerals as chlorides andfreeing the metallie sulphur and reducing the ferric chloride lo theferrous condition: separating the pregnant solution containing saidchlorides from the remainder of the ore; and precipitating the silverand copper with metals electro-positive to said silver and t-opper; andcoolinp the hot solution and precipitating lead chloride therefrom, andelectrolyzing said lead chloride to secure metallic lead and chlorineand using said chlorine to change the ferrous chloride formed by abovesaid treatment to ferric chloride and using last said ferric solutionfor the treatment of more ore.

In testimony whereof I have signed my name to the specification.

NIELS C. CHRISTENSEN.

